Easy Summation

Limits: 1s, 512 MB

Little Arya is growing up fast and now she can count the numbers. The problem with her counting is that she can count only the odd numbers in a sequence always starts from 1 such as 1, 3, 5, 7 and so on. Now, she wants to add them up and wants to find the summation of these numbers. Please help her.

This is a companion discussion topic for the original entry at https://toph.co/p/easy-summation